docs: Add note about setting correct kubelet work dir for k0s

[soenkeliebau]

Description

K0s has a non default kubelet work dir which needs to be configured when deploying secret operator.

Please add a description here. This will become the commit message of the merge request later.

Definition of Done Checklist

• Not all of these items are applicable to all PRs, the author should update this template to only leave the boxes in that are relevant
• Please make sure all these things are done and tick the boxes

Reviewer

• Documentation added or updated. Follows the style guide.

Acceptance

• Feature Tracker has been updated
• Proper release label has been added
• Links to generated (nightly) docs added
• Release note snippet added
• Add type/deprecation label & add to the deprecation schedule
• Add type/experimental label & add to the experimental features tracker

[sbernauer]

Thanks!